fix: watch now correctly diffs against previous run and shows "no changes" (#77)

findLatestArtifact accepts an excludePath param so watch can skip the
artifact it just wrote. When runs are identical, shows "✓ No changes
since last run" instead of silently falling through.

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: KryptosAI

src/commands/watch.ts

@@ -23,14 +23,18 @@ async function runWatchOneShot(
   const outPath = await writeRunArtifact(artifact, outDir);
 
   // Find the PREVIOUS run for this target (excluding the one just written)
-  const latestPath = await findLatestArtifact(outDir, target.targetId);
-  if (latestPath && latestPath !== outPath) {
-    const previousRaw = await readArtifact(latestPath);
+  const previousPath = await findLatestArtifact(outDir, target.targetId, outPath);
+  if (previousPath) {
+    const previousRaw = await readArtifact(previousPath);
     if (previousRaw.artifactType === "run") {
-      const previous = previousRaw;
-      const diffResult = diff(previous, artifact);
+      const diffResult = diff(previousRaw, artifact);
 
-      process.stdout.write(formatOutput(diffResult, options.format as "terminal" | "json") + "\n");
+      if (diffResult.summary.regressions === 0 && diffResult.summary.recoveries === 0 && diffResult.summary.added === 0 && diffResult.summary.removed === 0) {
+        process.stdout.write(formatOutput(artifact, options.format as "terminal" | "json") + "\n");
+        process.stdout.write(`${c(ANSI.green, "✓ No changes")} since last run\n`);
+      } else {
+        process.stdout.write(formatOutput(diffResult, options.format as "terminal" | "json") + "\n");
+      }
       process.stdout.write(`${c(ANSI.dim, `Artifact: ${outPath}`)}\n`);
 
       if (options.failOnRegression && diffResult.summary.regressions > 0) {

src/storage.ts

@@ -28,17 +28,19 @@ export async function writeRunArtifact(
   return filePath;
 }
 
-export async function findLatestArtifact(outDir: string, targetId: string): Promise<string | null> {
+export async function findLatestArtifact(outDir: string, targetId: string, excludePath?: string): Promise<string | null> {
   const slug = slugify(targetId);
   const suffix = `--${slug}.json`;
   try {
     const entries = await readdir(outDir);
     const matching = entries
       .filter(f => f.endsWith(suffix))
       .sort()
-      .reverse();
+      .reverse()
+      .map(f => path.join(outDir, f))
+      .filter(f => f !== excludePath);
     if (matching.length === 0) return null;
-    return path.join(outDir, matching[0]!);
+    return matching[0]!;
   } catch {
     return null;
   }